Abstract: A bottom-incidence type photo-sensing device has a pn junction, as a photo-sensing region, formed by selectively providing a first region of a second conductivity type in a portion of a semiconductive layer of a first conductivity type. The first region is surrounded by a second region of the second conductivity type formed in the semiconductive layer, and the second region is of the same or larger depth as or that of the first region. Even when light is directed to outside of the photo-sensing region, extra charges generated therein are absorbed by the second region and the flow of extra charges into the photo-sensing region is prevented.

Abstract: A semiconductor photodetector comprising a photodiode chip, a header for mounting the chip, a receptacle, and a ferrule for holding an end of an optical fiber. The photodetector does without a lens. A dielectric layer covers a periphery of the photodiode chip for shielding it from incidence of extra light beams by reflecting or absorbing light. Omission of a lens reduces the costs of parts and assembly. Since no light beams enter the peripheral part of photodiode chip, no delayed photocurrent is produced. Reproduced signals are immune from deformation or delay of phase. The photodetector facilitates wide prevalence of optoelectronic communication.

Abstract: A semiconductor light source for transmitting light signals of digital or analog data having a laser diode and a photodiode for monitoring the output power of the laser diode. The driving current of the laser diode is adjusted by the photocurrent of the monitoring photodiode. The photodiode has a light receiving region at a center enclosed by an annular electrode and a light non-receiving region outside the annular electrode. If leak light beams entered the non-receiving region, delayed photocurrent is produced. The delayed photocurrent misleads the control of the laser diode. This invention provides a non-receiving region of the photodiode with a dielectric layer for reflecting or absorbing light beams in order to preventing the light beams from producing the delayed photocurrent.

Abstract: A low doped semiconductive layer is formed on a semiconductor substrate of a highly doped first conductivity type, and a first region of a highly doped second conductivity type is selectively formed at a portion of the semiconductive layer. In a top-incidence type photo-sensing device having a pn junction area of the above structure as a photo-sensing region, the first region is surrounded by a second region of the second conductivity type formed at a portion of the semiconductor layer. The second region has the same or a larger depth as that of the first region. Thus, even if light is directed to the outside of the photo-sensing region, extra charges generated therein are absorbed by the second region and the flow of extra charges into the photo-sensing region is prevented.

Abstract: A photodiode comprises e.g. an n-type semiconductor layer, a p-type semiconductor region selectively formed in a central part from a surface of the n-type semiconductor layer, a dish-like shaped pn-junction therebetween, an annular electrode formed on the p-type region, an electrode formed on the other side of the n-type semiconductor layer, and a dielectric layer deposited on the n-type semiconductor layer for preventing light from attaining to the semiconductor layer by reflecting a dielectric multilayer consisting of two different media having effective thicknesses equal to one fourth of the wavelength of the light.

Abstract: An InGasAs/InP type PIN photodiode including an n-InP substrate, an n-InGaAs layer arranged on a surface of the substrate and a p-InGaAs layer comprising a portion of the n-InGaAs layer diffused with a p-type impurity. A ring-like p-electrode is arranged to encircle the p-InGaAs layer and a portion of the p-InGaAs layer encircled by the p-electrode is formed to a recess having a depth of less than 2.0 .mu.m. In addition, the thickness of the p-InGaAs layer is formed to be larger than 3.0 .mu.m. The PIN photodiode is arranged so that light is introduced into the recess.

Abstract: This invention relates to an electrode structure formed on a p-type III-V compound semiconductor and a method of forming the same. An electrode can by easily formed with a low ohmic contact resistance and formed without degrading a semiconductor element. The electrode structure includes an Au alloy layer formed on a p-type III-V compound semiconductor, a Ti or Cr stopper layer formed on the Au alloy layer, and an Au layer formed on the stopper layer.